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Reply To: | Classification, clustering, and phylogeny estimation |
Date: | Tue, 12 Nov 2002 18:49:34 -0600 |
Content-Type: | text/plain |
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J. Douglas Carroll wrote:
> I had thought at the time that perhaps
> David and Mark Rorvig, prior to Rorvig's tragic and untimely death last
> year, had put together such a program. While I gather from this message
> from David that, instead, Michael Trosset (who was also involved in the
same
> DIMACS Workshop on MDS Algorithms I mentioned in that earlier e-mail
addressed
> to Jim) has done so.
Following our presentation at DIMACS, Michael recommended an approach to the
computations that scaled better than what we had proposed to write. Both Dr.
Carroll's consultation at CSNA and Michael's assistance at DIMACS were
extremely helpful.
[...]
> In fact, not only are metric solutions (in the samedimensionality)
> usually as good as nonmetric ones, there is considerable empirical and
> theoretical evidence that, for certain types of data, they are in fact
BETTER--
> being less susceptible to various degeneracies and quasi-degeneracies that
> can affect many nonmetric MDS analyses, if the data exhibit certain
characteristics that
> are not at all unusual in the case of realistic proximity data from
various domains.
This is *exactly* what Mark and I discovered with his analysis of the TREC
data.
Dave Dubin
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